A method for producing a thermal wrap utilizing a superabsorbent polymer and, more particularly, a method for producing an aromatic thermal wrap that can be packaged in porous sachets as a dry, hydratable mixture that can be hydrated by the user and then chilled or heated prior to use.
Superabsorbent polymers, including, but not limited to polymers such as polysaccharides, polyacrylates, and carboxymethylcellulose, are well known in the art for their ability to absorb many times their own weight, and sometimes hundreds of times their own weight, in water. The hydrated superabsorbent polymer typically forms a gel that substantially retains the thermal properties of water while simultaneously immobilizing the water in the gel material. Such gels are frequently used in thermal wraps that can be warmed, typically by heating the gel in a microwave oven or other warming device, or frozen by placing the thermal pack in a freezer.
Cold and hot thermal wraps are commonly used as a first treatment for minor injuries, such as sprains and bruises. The thermal wrap is applied directly to the injured area. Lowering the local body temperature near a minor injury during the first few hours after the injury occurs will cause the blood vessels to contract, and limit internal bleeding and swelling near the injury situs. After the body has repaired itself sufficiently to stop undesirable internal bleeding, typically approximately 24 hours after the injury occurred, application of heat to the injured region will cause the blood vessels expand, thereby increasing the flow of blood to the site of the injury, and speeding the healing process.
The application of heat is also a common method of treating temporary or chronic pain. Such therapeutic heat treatments are used for conditions that include general body aches, stiffness in muscles and joints, nerve pain, rheumatism, and the like. Generally, the afflicted area is warmed by applying a heating element such as a thermal wrap directly to the aching area.
A common type of thermal wrap is produced by hydrating a superabsorbent polymer (SAP) to create a gel, and encapsulating the gel in an impermeable, sealed, plastic container. For example, in U.S. Pat. No. 3,545,230, Morse discloses a flexible cooling device comprising an insoluble hydrophilic gel (made from, e.g., carboxymethylcellulose) sealed in a flexible packaging material that can be frozen. A disadvantage of sealing the gel in a package is that the product must be hydrated during manufacture. The hydrated product is much heavier and voluminous than the unhydrated polymer, and therefore shipping, storing, and displaying the hydrated product is more difficult.
In U.S. Pat. No. 6,017,606, Sage et al. discloses a reusable thermal compress wherein a superabsorbent polymer is disposed within a water permeable fabric. The water permeable fabric is gel retaining, and so the user can hydrate the compress immediately prior to use.
In some situations, it may provide additional physical and/or psychological benefit and comfort to the user of a thermal wrap to additionally experience a pleasant and/or therapeutic aroma when using the thermal wrap. In addition to potential therapeutic benefits that certain aromatics might provide, if a pleasant aroma enhances the user""s enjoyment of the thermal wrap, then the user is likely to beneficially continue application of the thermal wrap for a longer period of time.
The use of aromatic compounds with a SAP is known in the art. In U.S. Pat. No. 4,961,493 to Kaihatsu, for example, an aromatic package is disclosed wherein an aromatic liquid or powder is dissolved in a solvent comprising 50 wt % ethanol and 50 wt % water, and then combined with a gelling agent, such as a SAP, and placed in a gas permeable and liquid impermeable package. Kaihatsu does not contemplate or suggest the use of the aromatic package as a thermal wrap, however. A disadvantage of the aromatic package disclosed by Kaihatsu is that the aromatic compound must be dissolved in a solvent (in the disclosure, a water/ethanol mixture) prior to combining the solvent/aromatic compound mixture with the gelling agent. Therefore, the aromatic package must be hydrated during manufacture, complicating the shipping, storing, and displaying requirements for the product. Moreover, many aromatics, particularly oil-based aromatics, are not dissolvable in water, thereby requiring the use of an alternative solvent such as ethanol.
It would be useful to mix a SAP with an aromatic compound (or a mixture thereof), that could by hydrated by the user just prior to use. It has been found, however, that if liquid aromatic compounds such as camphor, menthol, eucalyptus, essential oils, and/or aromatic oils are combined with a SAP gelling agent directly, without first hydrating the SAP, the superabsorbent polymer tends to agglomerate or clump together, thereby preventing or hindering the ability of the SAP to absorb water and form a gel.
An aromatic thermal wrap comprises a mixture of one or more liquid aromatic compounds that are absorbed and/or adsorbed into a porous silica powder and then mixed with a superabsorbent polymer. The mixture is placed in water permeable sachets. The aromatic thermal wrap can be manufactured, shipped, and stored without hydrating the superabsorbent polymer, thereby significantly simplifying handling of the product. The end-user hydrates the thermal wrap, and optionally heats or cools it prior to application, producing a thermal wrap that also provides a pleasant, and potentially health-promoting aroma.
In one embodiment of the invention, the thermal wrap sachets are produced in a regular planar array having individually separable pockets that can be utilized individually or in any convenient combination.
The aromatic compounds usable in accordance with the present invention include camphor, menthol, and essential oils. A carrier oil may be combined with the essential oils to moderate the intensity of the aroma.